Showing papers by "Kamaruzzaman Sopian published in 2016"

A review of organic small molecule-based hole-transporting materials for meso-structured organic-inorganic perovskite solar cells

Abstract: This review summarizes the current designs and development of new types of organic small molecules as a hole-transporting material (HTM) in a meso-structured perovskite solar cell (PSC). The roles of each layer in the meso-structured perovskite device architecture are elaborated and the employment of new types of organic HTMs in the device is compared with the commercially available HTM spiro-OMeTAD in terms of the properties, device performance and stability. The studies found that nearly half of the new synthesized and pristine HTMs have comparable or better photovoltaic properties than those of doped spiro-OMeTAD. These HTMs have the characteristics of a fused planar core structure with extended π-conjugated lengths and electron-donating functional groups, which are believed to contribute to their high intrinsic conductivity and help make them an alternative to spiro-OMeTAD as a better HTM in meso-structured PSCs. Some of the devices based on the new synthesized HTMs even have longer device lifetimes than their spiro-OMeTAD-based PSC counterparts. Moreover, studies found that the cost per gram (Cg) and cost-per-peak Watt (Cw) of synthesized HTMs can be reduced via minimizing the number of synthesis steps and by optimization of the starting materials in order to yield low-cost HTMs for meso-structured PSC applications.

Dye-sensitised solar cells: Development, structure, operation principles, electron kinetics, characterisation, synthesis materials and natural photosensitisers

Abstract: The energy economy is highly dependent on oil, coal and natural gas, which constitute 37%, 27% and 20% of energy usage, respectively. However, the reserves of fossil fuels (e.g., crude oil) are limited and could run out in approximately 40 years based on a daily consumption of 82.5 million barrels and the current reserves to production (R/P) ratio. Solar energy is the source of nearly all energy on Earth. Of all renewable power sources, solar energy is the most easily exploitable, inexhaustible, quiet, and adaptable to different applications. Photovoltaic cells (PVCs) are devices that directly convert sunlight into electricity without pollution, sound, or moving parts, which makes them long-lasting and dependable. PVCs use an elegant method to take advantage of sunlight. Solar cells offer one of the most promising and environmentally friendly methods for producing electricity. This paper reviews the emergence, principles, electron kinetics and components of PVCs with a focus on the molecular engineering of several metal complexes, organic dyes and natural dyes that are used as photosensitisers in dye-sensitised solar cells (DSSCs).

The role of climatic-design-operational parameters on combined PV/T collector performance: A critical review

Abstract: PV/T technology attracted numerous researchers and professionals during the last decades. There are many review papers in the literature evaluated the R&D aspects of PV/T collectors. In fact, there are abundant of case studies discussed the parameters of climate, design and operational conditions affected the PV/T collector performance. But, a comprehensive compilation of the information of those case studies is still a missing link in the literature. Hence, this paper intended to review thoroughly the information regarding the parameters affecting the PV/T collector performance mainly and PV module performance partially. The parameters are supported with the most available R&D to measure the accurate influence of each parameter on the performance. The outcomes from the study are highlighted in lessons learned section.

Silicon back contact solar cell configuration: A pathway towards higher efficiency

Abstract: The back-contact crystalline silicon solar cell represents an advanced configuration in which inter-digitated positive and negative contacts are placed on the rear surface. Highest conversion efficiency, elimination of shading losses, co-planarity of cell interconnections, and uniform black appearance, represent some of the most significant features of this type of solar cell. However, the manufacturing process complexity leads to significantly higher production cost making it difficult to compete with conventional mono and poly crystalline Si-based Photovoltaics industry. Over the years, an increasing number of researchers have reported on methods and processes aimed at reduction in manufacturing cost. This review paper attempt an extensive review of several categories of back-contact silicon solar cells, relevant design innovations, specific cost advantages especially in terms of using lower lifetime materials, their efficiency advantages in terms of geometry and wafer type, and their manufacturing technologies. In addition, available simulation tools for numerical investigation on back-contact structures and advanced device concepts have also presented in order to better understand underlying physical considerations in terms of passivation, both surface and volume, and minority carrier lifetime.

Research and development efforts on texturization to reduce the optical losses at front surface of silicon solar cell

Abstract: Silicon wafer-based solar cell contributes to about 92% of the total production of photovoltaic cells. An average of 30% of the incident light is lost via reflection from the front surface of the silicon solar cell, thus reducing the cell's power conversion efficiency. Texturization is a process of producing the desired unevenness on the surface of solar cell. It is well known as a practical solution to the limitation. Front surface texture reduces cell reflectivity and contributes to more photocurrent generation within active materials. The research and development efforts to reduce the optical losses via texturization are reviewed in this paper. The mechanisms of optical loss reduction, desirable texture feature, methods of texturization, side effects of texturization, and its compatibility with other optical enhancements for crystal silicon cell are elaborated upon. Front surface texture is associated with minimizing optical loss, and negatively affecting carrier and electrical losses. The importance of texturization for crystalline silicon is briefly related with thin film amorphous silicon solar cell to fully encompass this topic. Lesson learned and conclusion is highlighted in the last section.

Heat Transfer Enhancement for PCM Thermal Energy Storage in Triplex Tube Heat Exchanger

Abstract: Thermal energy storage is critical for reducing the discrepancy between energy supply and energy demand, as well as for improving the efficiency of solar thermal energy systems. Among the different types of thermal energy storage, phase-change materials (PCM) thermal energy storage has gained significant attention recently because of its high energy density per unit mass/volume at nearly constant temperature. This study experimentally investigates the using of a triplex tube heat exchanger (TTHX) with PCM in the middle tube as the thermal energy storage to power a liquid desiccant air-conditioning system. Four longitudinal fins were welded to each of the inner and middle tubes as a heat transfer enhancement in the TTHX to improve the thermal performance of the thermal energy storage. The average temperature of the PCM during the melting process in the TTHX with and without fins was compared. The PCM temperature gradients in the angular direction were analyzed to study the effect of the natural convection ...

Review: Survey of the control strategy of liquid desiccant systems

Abstract: This paper presents the survey of various models of the control strategy of liquid desiccant systems. A basic description of liquid desiccants concept is given first and some specifications of the main liquid desiccants are summarized and listed in table. Next, heat and mass transfer process and liquid desiccant cooling systems are described briefly. Furthermore, current research on control strategies for liquid desiccant systems is then discussed in detail. Finally, summary and conclusions are presented according to the collected information about the control and optimization of liquid desiccant systems.

Energy and exergy analysis of hybrid solar drying system

Abstract: In this study it was performed energy and exergy analysis of salted silver jewfish using a hybrid solar drying system (HSDS). An HSDS consisted of V-groove solar 216 Ahmad Fudholi et al. air collector, fans, rotating rack-drying chamber, diesel burner and PV array. At an average solar radiation of 540 W/m and a mass flow rate of 0.0778 kg/s, the collector efficiency and drying system efficiency were about 41% and 23%, respectively. The total energy required used is 89.9 kWh and the solar energy contribution is 66% (59.6 kWh) of the total energy. The diesel burner and fans power used is 29 % (25.8 kWh) and 5 % (4.5 kWh), respectively. Specific energy consumption was 2.92 kWh/kg. Moreover, the exergy efficiency of solar drying ranged from 17% to 44%, with an average of 31%. The improvement potential was 106 W to 436 W, with an average of 236 W.

Review on matrix thermal absorber designs for solar air collector

Abstract: Solar thermal absorber is the main component of solar air collector. It absorbs solar radiation and converting energy received to thermal energy and transferring the energy by means of convection to working fluid, producing elevated air temperature output. Among thermal absorber used in solar air collector applications, permeable matrix thermal absorber is one of the promising thermal absorbers that delivers high thermal efficiency. Absorber topology, flow routing and materials contribute a significant portion towards thermal performance and overall thermal efficiency of collector and many research are being actively done in these areas. This review shall focus on the advances of topology designs, enhancement methods, thermal performance and absorber materials currently available for matrix type of solar air collector. Essential attributes influencing thermal performance of solar air collector with matrix absorber are also highlighted in this article.

Electrocoagulation by solar energy feed for textile wastewater treatment including mechanism and hydrogen production using a novel reactor design with a rotating anode

Abstract: This paper describes the treatment of textile wastewater using a unique design of an electrocoagulation (EC) reactor with a rotating anode. The effects of various operational parameters such as rotational speed of the anode, current density (CD), recirculation flow rate, operational time (RT) and continuous flow regime on the efficiency of pollutant removal in terms of chemical oxygen demand (COD) and colour were examined. The mechanisms of EC treatment and hydrogen production were also evaluated. In addition, the model verification was an attempt to study the passivation and adsorption phenomena. The results indicated that the optimum conditions were achieved at CD = 4 mA cm−2, RT = 10 minutes and rotational speed = 150 rpm, where the operating cost was 0.072 US$ per m3. The removal efficiencies of COD and colour were 91%, 95% for the batch system and 91.5%, 95.5% for the continuous flow system respectively. Zeta potential values indicate that the chemical interaction happened, and XRD analysis of the sludge produced reveals that the reaction is a chemo-adsorption type, where the final product is environmentally friendly (aliphatic sludge). Hydrogen production was enhanced under the optimal conditions to produce 12.45%, reducing the power consumption by 9.4%. The passivation and adsorption resistance values validate the removal rate of pollutants.

Heterojunction Cr2O3/CuO:Ni photocathodes for enhanced photoelectrochemical performance

Abstract: Heterojunction p-type photoelectrodes consisting of chromium oxide (Cr2O3) and copper oxide (CuO)-doped nickel (Ni) were prepared using aerosol-assisted chemical vapour deposition (AACVD) and spin-coating. All samples were photoresponsive and showed a photocathodic current in 0.5 M Na2SO4 under simulated solar illumination. The photocathode with an optimal composition of 3 layers of CuO and 0.5% Ni showed an enhanced photoactivity relative to bare Cr2O3. Based on the optical characterization and the flatband potential calculation, the fabricated Cr2O3, Cr2O3/CuO and Cr2O3/CuO:Ni can absorb visible light, which enables the water reduction reaction. Moreover, electrochemical impedance spectroscopy revealed that the charge transfer resistance of Cr2O3/CuO:Ni was decreased. Thus, in the heterojunction structure, the photogenerated electrons in Cr2O3 were transferred to the CuO:Ni layer, which then contributes to a high photoactivity. The combined advantages of the two strategies (heterojunction and doping) provide favourable charge transport characteristics of the materials.

Drying of salted silver jewfish in a hybrid solar drying system and under open sun: Modeling and performance analyses

Abstract: This study investigated the thin-layer drying kinetics of salted silver jewfish in a hybrid solar drying system and under open sun. Ten drying models were compared with experimental data of salted silver jewfish drying. A new model was introduced, which is an offset linear logarithmic (offset modified Page model). The fit quality of the models was evaluated using the coefficient of determination (R2), root mean square error (RMSE), and sum of squared absolute error (SSAE). The result showed that Midilli et al. model and new model were comparable with two or three-term exponential drying models. This study also analyzed energy and exergy during solar drying of salted silver jewfish. Energy analysis throughout the solar drying process was estimated on the basis of the first law of thermodynamics, whereas exergy analysis during solar drying was determined on the basis of the second law of thermodynamics. At an average solar radiation of 540 W/m2 and a mass flow rate of 0.0778 kg/sec, the collector ef...

Performances analysis of greenhouse solar dryer with heat exchanger

Abstract: A greenhouse solar dryer with heat exchanger was tested for salted catfish in Perlis, Malaysia at average solar radiation of 626 W/m. The dryer consists of the heat pipe evacuated tube collector, electric heaters, blower, pumps, water tank, and green136 Ahmad Fudholi et al. house drying chamber. The average temperature of the drying chamber is 44C. The drying time is 18 h (8h day time and 10h night time). The total energy required used is 294.98 kWh and the solar energy contribution is 60 % of the total energy. The electric heaters, and blower-pump power used is 29 % and 11 %, respectively. The moisture extraction rate (MER) and specific moisture extraction rate (SMER) obtained of 6.3 kg/h and of 0.385 kg/kWh, respectively. The values for exergy efficiency varied between 29 % and 82 % with an average of 46 %. Economic analysis showed that system is a payback period about 1 year.

Photoelectrochemical water splitting performance of flower like ZnO nanostructures synthesized by a novel chemical method

Abstract: A flower like ZnO nanostructures are synthesized using by a novel chemical method without using any precipitating agent. Structural, morphological and optical properties are studied using powder XRD, FE-SEM, TEM and UV–Vis. spectroscopy measurements. The synthesized flower like ZnO nanostructures are in single hexagonal wurtzite phase with good crystalline nature. The average size of the flower like ZnO nanostructures is 50 nm visualized from FESEM images, which composed of 5 nm ZnO spherical nanoparticles. The formation mechanism for a flower like ZnO nanostructures are discussed in detail. Optical absorption spectrum of ZnO nanoflower showed a band gap of 3.25 eV. Photoelectrochemical water splitting performance is evaluated by current density measurement for different applied voltage. The improved photocurrent density is shown as 0.39 mA/cm at 0.6 V versus Ag/AgCl under simulated solar irradiation.

Hydrophilic carbon/TiO2 colloid composite: a potential counter electrode for dye-sensitized solar cells

Abstract: A new type of counter electrode (CE), composed of hydrophilic carbon (HC) particle and TiO2 colloid (HC/TiO2), was successfully prepared using doctor blade technique on fluorine-doped tin oxide substrate for dye-sensitized solar cell (DSSC). Properties of HC/TiO2 CE, including crystal structure, surface morphology, roughness, conductivity, and catalytic activity, were analyzed. Results showed that a HC/TiO2 CE with an average thickness of 1 µm contributed to high surface roughness. Cyclic voltammetry further revealed that HC/TiO2 CE displayed good catalytic activity similar to that of Pt electrode, which is mainly attributed to an addition of TiO2 in the electrode. DSSC was fabricated with HC/TiO2 CE. Under one sun illumination (AM 1.5, P in of 100 mWcm−2), the device exhibited an energy conversion efficiency of 1.9 %, which is comparable to 3.6 % of the cell with Pt electrode under the same experimental conditions. These findings suggest that HC/TiO2 CE is a promising alternative CE for low-cost DSSCs.

Green Material Prospects for Passive Evaporative Cooling Systems: Geopolymers

Abstract: Passive cooling techniques have been used mostly in countries with hot and arid climates such as Iran, Egypt, and India. However, the use of this important technology has not been seriously considered until a time of energy crisis, and consequently, environmental crisis scenarios, emerge. Scholars have renewed their interest in investigating passive cooling technology, particularly the aspects of new materials, thermal comfort, energy efficiency, new designs, climate, and environmental considerations. This review paper highlights the opportunities to use green materials, such as geopolymers, as evaporative cooling materials with different types of industrial and agricultural waste products as components. Novel ideas for passive cooling design using ancient and nature-inspired concepts are also presented to promote green technology for future applications.

Optimization of dye extraction from Cordyline fruticosa via response surface methodology to produce a natural sensitizer for dye-sensitized solar cells

Abstract: In the present work, the application of response surface methodology (RSM) for the optimization of process parameters in the chlorophyll extraction from Cordyline fruticosa leaves was performed. The absorbance of the extract obtained from the extraction process under different conditions was estimated using the D-optimal design in RSM. Three different process parameters such as the nature of organic solvent based on their boiling point (ethanol, methanol, and acetonitrile), pH (4–8) and extraction temperature (50–90 °C) were optimized for chlorophyll extraction. The effects of these parameters on the absorbance or concentration of the extract were evaluated using ANOVA results of quadratic polynomial regression. The results showed a high R 2 and adjusted R 2 correlation coefficients of 0.9963 and 0.9921 respectively. Moreover, the analysis of the final quadric model based on the design experiments indicated an optimal extraction condition of pH of 7.99, extraction temperature of 78.33 °C, and a solvent boiling point, 78 °C. The predicted absorbance was 1.006, which is in good agreement with the experimentally obtained result of 1.04 at 665 nm wavelength. The application of pigment obtained under the optimal condition was further evaluated as a sensitizer for the dye sensitized solar cells. Maximum solar conversion efficiency ( η ) of 0.5% was achieved for the C. fruticosa leaf extract obtained under the optimum extraction conditions. Furthermore, the exposure of the leaf pigment to 100 mW/cm 2 simulated sunlight yielded a short circuit photocurrent density ( I sc ) of 1.3 mA, open circuit voltage ( V oc ) of 616 mV, and a fill factor (ff) of 60.16%.

Effect of New Ellipse Design on the Performance Enhancement of PV/T Collector: CDF Approach

Abstract: Photovoltaic and thermal collectors are combined via a photo­voltaic/thermal (PV/T) collector system to increase collector efficiency. The efficiency of photovoltaic collectors is known to decrease when ambient temperature increases and vice versa. PV/T collector systems function by absorbing the heat gained from the sun via photovoltaic panels and by converting this heat into electrical energy. Simulations CFD have been investigated to explore the impact of different mass flow rates against photovoltaic and thermal efficiencies of PVT collector using FVM. New ellipse design of collectors have been modeled and investigated to generate hot water and electricity. In this simulation, the absorber collectors were assumed to be attached underneath the photovoltaic (PV) module, and water is used as a heat transfer medium in absorber collectors. The results shown that new ellipse absorber collector generates a combined PV/T efficiency of 74.3% with electrical efficiency of 13.78%. The efficiency of the PV/T system should be improved further by developed the surfaces between the absorber and solar panel (PV module). However, different types of PV cells, such as amorphous silicon cells with black mat surface properties, should be used to improve the thermal absorption of PV/T systems. Highlights: (i) A three-dimension hybrid photovoltaic/thermal solar collector module was performed in CFD software; (ii) The results agree with those obtained through steady-state characterization; (iii) The simultaneous use of new ellipse design of absorber, which absorbs much more thermal energy compared to other normal designs, increase thermal and electrical efficiency significantly.